drivers/watchdog/rt2880_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Ralink RT288x/RT3xxx/MT76xx built-in hardware watchdog timer
   4  *
   5  * Copyright (C) 2011 Gabor Juhos <juhosg@openwrt.org>
   6  * Copyright (C) 2013 John Crispin <john@phrozen.org>
   7  *
   8  * This driver was based on: drivers/watchdog/softdog.c
   9  */
  10
  11 #include <linux/clk.h>
  12 #include <linux/reset.h>
  13 #include <linux/module.h>
  14 #include <linux/kernel.h>
  15 #include <linux/watchdog.h>
  16 #include <linux/moduleparam.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/mod_devicetable.h>
  19
  20 #include <asm/mach-ralink/ralink_regs.h>
  21
  22 #define SYSC_RSTSTAT                    0x38
  23 #define WDT_RST_CAUSE                   BIT(1)
  24
  25 #define RALINK_WDT_TIMEOUT              30
  26 #define RALINK_WDT_PRESCALE             65536
  27
  28 #define TIMER_REG_TMR1LOAD              0x00
  29 #define TIMER_REG_TMR1CTL               0x08
  30
  31 #define TMRSTAT_TMR1RST                 BIT(5)
  32
  33 #define TMR1CTL_ENABLE                  BIT(7)
  34 #define TMR1CTL_MODE_SHIFT              4
  35 #define TMR1CTL_MODE_MASK               0x3
  36 #define TMR1CTL_MODE_FREE_RUNNING       0x0
  37 #define TMR1CTL_MODE_PERIODIC           0x1
  38 #define TMR1CTL_MODE_TIMEOUT            0x2
  39 #define TMR1CTL_MODE_WDT                0x3
  40 #define TMR1CTL_PRESCALE_MASK           0xf
  41 #define TMR1CTL_PRESCALE_65536          0xf
  42
  43 struct rt2880_wdt_data {
  44         void __iomem *base;
  45         unsigned long freq;
  46         struct clk *clk;
  47         struct reset_control *rst;
  48         struct watchdog_device wdt;
  49 };
  50
  51 static bool nowayout = WATCHDOG_NOWAYOUT;
  52 module_param(nowayout, bool, 0);
  53 MODULE_PARM_DESC(nowayout,
  54                 "Watchdog cannot be stopped once started (default="
  55                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  56
  57 static inline void rt_wdt_w32(void __iomem *base, unsigned int reg, u32 val)
  58 {
  59         iowrite32(val, base + reg);
  60 }
  61
  62 static inline u32 rt_wdt_r32(void __iomem *base, unsigned int reg)
  63 {
  64         return ioread32(base + reg);
  65 }
  66
  67 static int rt288x_wdt_ping(struct watchdog_device *w)
  68 {
  69         struct rt2880_wdt_data *drvdata = watchdog_get_drvdata(w);
  70
  71         rt_wdt_w32(drvdata->base, TIMER_REG_TMR1LOAD, w->timeout * drvdata->freq);
  72
  73         return 0;
  74 }
  75
  76 static int rt288x_wdt_start(struct watchdog_device *w)
  77 {
  78         struct rt2880_wdt_data *drvdata = watchdog_get_drvdata(w);
  79         u32 t;
  80
  81         t = rt_wdt_r32(drvdata->base, TIMER_REG_TMR1CTL);
  82         t &= ~(TMR1CTL_MODE_MASK << TMR1CTL_MODE_SHIFT |
  83                 TMR1CTL_PRESCALE_MASK);
  84         t |= (TMR1CTL_MODE_WDT << TMR1CTL_MODE_SHIFT |
  85                 TMR1CTL_PRESCALE_65536);
  86         rt_wdt_w32(drvdata->base, TIMER_REG_TMR1CTL, t);
  87
  88         rt288x_wdt_ping(w);
  89
  90         t = rt_wdt_r32(drvdata->base, TIMER_REG_TMR1CTL);
  91         t |= TMR1CTL_ENABLE;
  92         rt_wdt_w32(drvdata->base, TIMER_REG_TMR1CTL, t);
  93
  94         return 0;
  95 }
  96
  97 static int rt288x_wdt_stop(struct watchdog_device *w)
  98 {
  99         struct rt2880_wdt_data *drvdata = watchdog_get_drvdata(w);
 100         u32 t;
 101
 102         rt288x_wdt_ping(w);
 103
 104         t = rt_wdt_r32(drvdata->base, TIMER_REG_TMR1CTL);
 105         t &= ~TMR1CTL_ENABLE;
 106         rt_wdt_w32(drvdata->base, TIMER_REG_TMR1CTL, t);
 107
 108         return 0;
 109 }
 110
 111 static int rt288x_wdt_set_timeout(struct watchdog_device *w, unsigned int t)
 112 {
 113         w->timeout = t;
 114         rt288x_wdt_ping(w);
 115
 116         return 0;
 117 }
 118
 119 static int rt288x_wdt_bootcause(void)
 120 {
 121         if (rt_sysc_r32(SYSC_RSTSTAT) & WDT_RST_CAUSE)
 122                 return WDIOF_CARDRESET;
 123
 124         return 0;
 125 }
 126
 127 static const struct watchdog_info rt288x_wdt_info = {
 128         .identity = "Ralink Watchdog",
 129         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 130 };
 131
 132 static const struct watchdog_ops rt288x_wdt_ops = {
 133         .owner = THIS_MODULE,
 134         .start = rt288x_wdt_start,
 135         .stop = rt288x_wdt_stop,
 136         .ping = rt288x_wdt_ping,
 137         .set_timeout = rt288x_wdt_set_timeout,
 138 };
 139
 140 static int rt288x_wdt_probe(struct platform_device *pdev)
 141 {
 142         struct device *dev = &pdev->dev;
 143         struct watchdog_device *wdt;
 144         struct rt2880_wdt_data *drvdata;
 145         int ret;
 146
 147         drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
 148         if (!drvdata)
 149                 return -ENOMEM;
 150
 151         drvdata->base = devm_platform_ioremap_resource(pdev, 0);
 152         if (IS_ERR(drvdata->base))
 153                 return PTR_ERR(drvdata->base);
 154
 155         drvdata->clk = devm_clk_get(dev, NULL);
 156         if (IS_ERR(drvdata->clk))
 157                 return PTR_ERR(drvdata->clk);
 158
 159         drvdata->rst = devm_reset_control_get_exclusive(dev, NULL);
 160         if (!IS_ERR(drvdata->rst))
 161                 reset_control_deassert(drvdata->rst);
 162
 163         drvdata->freq = clk_get_rate(drvdata->clk) / RALINK_WDT_PRESCALE;
 164
 165         wdt = &drvdata->wdt;
 166         wdt->info = &rt288x_wdt_info;
 167         wdt->ops = &rt288x_wdt_ops;
 168         wdt->min_timeout = 1;
 169         wdt->max_timeout = (0xfffful / drvdata->freq);
 170         wdt->parent = dev;
 171         wdt->bootstatus = rt288x_wdt_bootcause();
 172
 173         watchdog_init_timeout(wdt, wdt->max_timeout, dev);
 174         watchdog_set_nowayout(wdt, nowayout);
 175         watchdog_set_drvdata(wdt, drvdata);
 176
 177         watchdog_stop_on_reboot(wdt);
 178         ret = devm_watchdog_register_device(dev, &drvdata->wdt);
 179         if (!ret)
 180                 dev_info(dev, "Initialized\n");
 181
 182         return 0;
 183 }
 184
 185 static const struct of_device_id rt288x_wdt_match[] = {
 186         { .compatible = "ralink,rt2880-wdt" },
 187         {},
 188 };
 189 MODULE_DEVICE_TABLE(of, rt288x_wdt_match);
 190
 191 static struct platform_driver rt288x_wdt_driver = {
 192         .probe          = rt288x_wdt_probe,
 193         .driver         = {
 194                 .name           = KBUILD_MODNAME,
 195                 .of_match_table = rt288x_wdt_match,
 196         },
 197 };
 198
 199 module_platform_driver(rt288x_wdt_driver);
 200
 201 MODULE_DESCRIPTION("MediaTek/Ralink RT288x/RT3xxx hardware watchdog driver");
 202 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org");
 203 MODULE_LICENSE("GPL v2");